DESCRIPTION (Adapted from applicant's description): Small intestinal epithelial cells (enterocytes) have a very high energy demand due to their intensive absorptive and secretory functions and the high rate of cell turnover. Glutamine is the dominant energy source for enterocytes and it takes part in prevention of gut atrophy, regulation of blood flow, and protection against heat shock induced cell death. The current proposal aims at elucidating the cellular mechanisms of glutamine action on enterocytes using the CaCo-2 cell in vitro model. The investigator will examine the role of glutamine in the protective process when supplied from the apical side. Steps in translocation and interaction of E. Coli with enterocytes will be examined by structural and functional studies. Sodium pump activity will be evaluated along with other metabolic manipulations. Ultrastructural analysis will be performed with special emphasis on tight junction proteins. Parallel studies will be carried out in weanling rabbit ileal loops for comparative analysis in an in vitro system.